Proportional divider



July 17, 1951 PROPORTI F. JOY

oNAL DIVIDER Filed Dec. 1e. 194e amy.

Patented July 17, 1951 UNITED vSTATES PATENT OFFICE vPROPOR'IIONALDIVIDER Joseph F. Joy, Pittsburgh, Pa., assignor to Joy ManufacturingCompany, Pittsburgh, Pa., a corporation of *P ennsylvania ApplicationDecember 16, 1946'Serial No, 116,523

This invention relates to drawing instruments and more particularly toan improved proportional divider having improved means for adjusting thepivotal point between the divider arms or leg members and for iirmlyholding the pivotal point in adjusted position, so that measurementstaken from a drawing or the like may be increased or decreased accordingto scale as desired.

Proportional dividers of known makes usually have the V( iivider arms orleg members thereof longitudinally slotted, and passing through theslots is a pivot pin or bolt having clamping means associated therewithto hold the slotted divider arms or leg members intheir differentpositions of adjustment. Such lknown arrangements are not onlyrelatively complicated and expensive to manufacture but are also subjectto inadvertent slippage which hinders proper use of the instru,- ment.The proportional divider of the present invention is provided Ywithsolid, non-slotted leg members, andthe pivot and clamp is'arrangedexternally of the non-slotted divider arms or leg members in anovelmanner so that the pivot may be. nrrnly held in .its positions ofadjustment. Furtherfby making the leg members solid and arrangingthetpivot and clamp externally thereof,

it is found possible to decrease the cost of manu` facture while, at thesaine time, making the instrument more reliable in use.

It is accordingly an object of the present invention to provide animproved drawing instrument whichv has many advantages over knowndevices. A further object is to provide an improved proportional dividerhaving improved pivot means whereby the possibility ,of the selectedadjustment of the divider arms or leg members becoming disturbed duringuse is substantially avoided. Yet another object is to provide animproved proportional divider` having solid, non-slotted divider arms orleg members and improved clamping means arranged externally of thedivider arms or leg members for iirmly holding the pivot point thereofin adjusted position. A further object is to provide an improvedproportional divider of a design which eliminates Acostly machiningoperations, enabling manufacture at less cost. A still further object isto provide an improved proportional .divider which not only has decidedadvantages over known devices from the standpoint of manufacture andcost, but one which also may be used with greater accuracy and facility.Yet another object is the provision of an instrument of the abovecharacter which is extremely simple in construction, requiring but fewcomponent parts, thoroughly reliable and efeient irl its purposes,

17 Claims. (Cl. 33-150) and inexpensive to manufacture, as well asstrong and durable. These and other objects and advantages of theinvention will, however, hereinafter more fully appear.

In the accompany-ing drawing there are shown for purposes ofillustrationtwo forms which the invention may assume in practice.

In this drawing;

Fig'. 1 is a front elevational View of a proportional dividerconstructed in acoordance'with a preferred illustrative embodiment ofthe invention.

Fig. 2 is a view in central longitudinal section taken substantially online 2 2 of Fig. 1, with parts shown in full'.

Fig. 3 is an elevational view similar to Fig. 1, with the divider armsin extended position.

Fig. 4 is a detail sectional View taken on line -of Fig. 3, illustratingdetails of the pivot and clamp.

Fig. 5 is a detail sectional view taken on line 5-5 of Fig. 4, showingthe pivot structure.

Fig. 6 is a cross-sectional view taken centrally through the pivot online 6 6 of Fig. 2,

Figs. '7 and 8 are, respectively, end and side viewsv of the arm seat orbearing element.

Fig. 9 shows, in elevation, the combination spring and pivot disk whichis used at the pivot pointbetween the divider arms.

Fig'. 10 vis a cross-sectional view taken on line l-fl of 4Fig. 9.

Fig. 11 is a cross-sectional view taken on line II-ll of Fig. 2, showingthe arm seat and slot structure.

Fig. l2 is a fragmentary view in central longitudinalsection,illustrating a modied form of pivot and clamp.

Fig'. 13 is across-sectional view taken on line l3`l3 of Fig. 12. l

Fig. 14 is a cross-sectional view taken on line Ill-'I4 of Fig. 12,showing the arm slot structure.

In b oth illustrative embodiments of the invention, there is shown aproportional divider of novel construction having solid, non-slotteddivider' arms or leg members and an improved pivot and clamp structurearranged externally of the divider arms for firmly holding theadjustment of the pivot while freely allowing adjustment of the dividerarms when desired. In the use of proportional dividers, it is ofttimesnecessary to take a large number of measurements with the dividers setin one proportion, and in doing this, it often happens that the positionof the pivot point becomes inadvertently shifted as ya result offrequent handling of the instru.-

ment, thus destroying the setting of the instrument and sometimescausing serious trouble in carrying out the work then in hand. By theuse of the improved external pivot and clamp of the present invention,the probability of such disturbance of the adjustment is very slight.Also, by the provision of the improved pivot and clamp structure of thepresent invention, the pivot of the divider arms may be adjusted througha relatively wide range without the limitations of the longitudinalslots, previously referred to, in the divider arms of conventionaldividers, and may be adjusted at any desired point between the extremelimits of the range of adjustment.

In the preferred illustrative construction shown in Figs. 1 to 11inclusive, the proportional divider has but six component parts, andincludes a pair of divider arms or leg members I and 2 which are of asolid, non-Slotted construction and are held together by an externalpivot or clamp structure, generally designated 3, of an improved design.The arms or legs are of a sturdy, though light, generally semi-circularcross section having plane inner adjacent surfaces 4 and curved outersurfaces 5. The outer arm surfaces are provided with numberedgraduations stamped or otherwise imposed thereon comprising a scale 6,divided into suitable units, so that the divider may be readily set atthe desired proportion. lIhe arms or legs are provided at their longsides with points 1, 1 and at their shorter sides with points 8, 8.

The improved pivot or clamp structure 3 includes a generally cylindricalpivot-box or outer casing 9 having a uniform central bore I0, and thecasing side walls are cut away or slotted at II to provide a seat I2 forthe arm or leg I passing through the casing. Thus the arm I is heldagainst pivotal movement with respect to the pivot-box 9 but is free toslide longitudinally in its seat I2 relative to the pivot-box. Adjoiningthe seat-slots II are segmental slots I3 extending circumferentiallythrough the casing walls and through which the other leg or arm 2passes, and the leg 2 is not only free to slide longitudinally withrespect to the pivot-box but also to swing relative to the pivot-boxwithin limits determined by the ends of the slots I3. Arranged in thecasing-bore I and seated at I4 against a shoulder provided at the bottomof the bore is a circular seat element or pivot bearing I5 for the legmember 2, and the element I5 is slotted or grooved transversely at I6 atits inner side to conform to the contour of the curved outer surface 5of the leg 2, as shown most clearly in Fig. 6. Thus a snug fit isprovided for the pivoted leg 2. The seat or bearing element I5, when theclamp is loosened, is free to turn in the casing-bore, thereby toprovide a swivel bearing for the pivoted leg 2 as the latter is swung inthe arcuate slots in the casing Walls. A combination spring and pivotdisk I'I, herein of dished form as shown in Fig. 10, affording someresiliency, is arranged within the casingbore between the inner planesurfaces 4, 4 of the divider arms, and threaded at I8 within the outerthreaded end of the casing-bore is a clamping nut I9 formed with aknurled grasping portion 20. When the nut is tightened, the divider armsare pressed toward one another, compressing the spring disk I'I to thedesired tension between the legs and clamping the element I5 tightlyagainst its seat I4, thereby firmly to hold the arm-pivot in adjustedposition and to secure ment I5 has a central opening 24 and the end.

wall of the pivot-box 9 is centrally cut away to provide for similarobservation of the corresponding indicating numeral on the arm 2.

The instrument is assembled, as shown in Figs. 2 and 5, and, uponassembly, the bearing element I5 is first placed in the bore I0 of thepivot-box against its seat I4. The arm 2 is next placed in the groove I6through the segmental slots I3, and the combination spring and pivotdisk I'I is next inserted in the casing bore II] against the inner planesurface 4 of the arm 2. The arm I is then slid in place in the seat I2and the clamping nut I9 may then be threaded into the casing-bore andtightened to hold the parts together. When in use, the divider may beset to the desired proportion by sliding both arms or legs I and 2 as aunit, when the arms are held together in closed position, relative tothe pivot-box or by sliding the pivot-box bodily relative to the arms,until the desired indicating numerals yare centered within theobservation openings 23 and 24. When the desired relation of the pivotarms has thus been made, the clamping nut I9 may be screwed down,compressing the combination spring and pivot disk II to the desiredtension between the divider arms. The instrument is thus made ready foruse. In operation, the leg I, by reason of its being snugly seated inthe slotseat I2 of the pivot-box, becomes firmly held to the box andmoves therewith, whereas the leg 2 seated in the bearing seat of theelement I5 which is rotatable relative to the pivotbox is free to movethrough the desired range of the segmental slots I3 in the casing.Obviously, the tension between the divider arms may be adjustedto thedesired degree by means of the clamping nut I9, thus regulating thepressure on the spring-disk I'I to the desired amount. By locating thedisk between the arms in the manner disclosed, the pivotal action of thearms is improved, thereby facilitating positioning of the arms. Byreason of the arm I held against pivotal movement relative to thepivot-casing and the clamping nut I9, possibility of change ofadjustment due to inadvertent slippage is substantially eliminated.Adjustment of the instrument from one ratio to another may be quicklyaccomplished simply by loosening the clamping nut and sliding the arms Iand '2 in and out of the pivotbox or sliding the pivot-box bodilyrelative to the arms until the desired setting of the pivot is obtained.

In the modified embodiment shown in Figs. l2, 13 and 14, the dividerarms, the pivot box, the clamping nut and the bearing element I5 for thearm 2 are generally like those of the embodiment above described. Inthis novel construction, the pivot box or casing 25 is segmentallyslotted at 26 and 21 to receive both arms or legs I and 2 so that botharms may swing relative to the casing Within limits determined by theends of the slots. Arranged in the casingbore is a pivot element 28similar to the bearing. element I5 and similarly transversely slotted oraseoeafz g-rooved at 29y at its inn-er side to` conform to. the curvedouter contour of the,l arm l. A clamping nut ."ill,l similar totheclamping, nut t9., engages the element 2'8. upon setting of the pivot..When the clamping nut is tightened, in the manner .0f the preferredembodiment, the combination spring and pivot dislr l1 between thedivider arms is compressed to the. desired tension, and the elements areheld rmly in position in the casing bore so that the. proper setting .ofthe pivot is made possible. By the provision of*A the rotat, ablebearing elements for each of the divider arms, it is. possible not onlyto. obtain firm setting of the pivot but also. swinging and slidingadjustment of the ar-ms is facilitated.- If desired, the bottom end wall.of the casing 125;. may be formed with a threaded aperture to receive asuitable annular, openfcentered screw plus s that the bearing element lmay be inserted in place or removed through the bottom end wall of thecasing Without disturbing the clamping nut. Otherwise, this embodimentof the invention is similar to that above described.

As a result of this invention an. improved draw:

ing instrument is provided which has [many advantages over previousdevices, in that the set-1 ting of the pivotal point between the arms isfacilitated and the possibility of inadvertent slip1 page of the pivotalpoint and longitudinal slip-A page .of the arms is substantiallyreduced. The improved dividers are of a simple and sturdy con:struction, and due to their novel design, may b e cheaply manufactured,since costly machining operations have Vbeen eliminated. By .the profvision .of the improved pivotal mounting for the arms, eliminatingexcessive friction between the parts, adjustment of the arms is maderelatively easy. These and other advantages vand .the man: ners of useof the improved drawing instrument Iwill be clearly apparent to thoseskilled in the art.

While there are in this vapplication specincally described two formswhich the invention may assume in practice, it will be understood thatthese forms of the same are shown for purposes of illustration and thatthe invention may .be fur: ther modied and embodied in various otherforms without departing from its spirit or .the scope of the appendedclaims.

What I claim as new and desire to secure by Letters Patent is:

1- .111:3 drawing pfstmml'l -O the. 99341-393381' described, a pair Vofrelatively `Yadju(stable arms, an Outer easing .a central .and Openingsthrough the walls thereof through which said arms pass, one of said.openings being in the form of Va. seat `for Aone .of .said arms to holdthe` latter against swinging movement relative to said `casingand the.other opening being inthe form of a segmental slot -ior- .permittinglimited swinging movement of said other arm relative to said casing, andadjustable clamping means secured Ato said casing for moving one oi saidarms toward the other to clamp said arms in adjusted position relativeyto said casing.V

2. In a proportional divider, a pair of relatively :adjustable dividerarms of solid cross section throughout their length and having pointedends, and a pivot and clamp device including a pivot box arrangedexternally of said arms and having openings in its side Walls throughwhich said arms pass and one of said openings being laterally elongatedto permit swinging movement of one of said arms relative to the otherand to said pivot box, and adjustable clamping means 6. associated withsaid pivot box f9.1'- .rlloving said :arms toward one anotherfritionaily to hold said swingable arm against swing-ille lllQYeHlglli.rela; tive tosaid other arm .and seid pivot bols.

s. In a proportional divider, a 'pail of reletively adjustable dividerarms having pointed ends, and a pivot and f-rictional clamp deviceincluding a .clamp and nii/Ot @9X arranged elle ternally of said armsand ha ing openings in its Side Walls through which said arms page,@Ollipressible .spring and pivot element between .Seid arms, .and asingle adjustable means. Secured t0 said pox and adjustable relativethereto .for mov-v ing one of said armsrelative to the other to compresssaid spring and pivOi 6191.119111? hold both arms lll adjusted positionrelative to said. box.-

1- In .an instrument or the Character `described, a pair of relativelyadilltohle @mls or solid cross section throughout their length, and apivot and clamp. .device .ingllldirls a unitary casing member arrangedexternally of said arms and .through which Said .arms estelle Sad deviceembodying a single adjustable Clamping element adjustably secured tosaid casing member acting on one of said arms to move the arms towardOne another t0 .Clamp both arms .lll adjusted Position with respectmsgid ,Casing member- -5- a proportional divider, e nail el leletlvelvadjustable divider arles having pointed ends, a cylindrical outer.casing llavlle clrllmf ferentially extending segmental slo s in thewalls thereof through which. Said ailes pas t0 permit limited Swingingmovement of the ernl's'rlliive to seid .casina and adjustable .Coaxial@lmplllg element ,Secured .lo said @eine aridr 'ed-lusiable relativethereto .for leg/ills one f' Seid alims toward. the. other l0. 01emeSaid' allllsln' adjusted Position relative te .Said easing? 6. vaproportional divider, a pair of relatively edelstahl@ divider' armshal/ille minted ends, an outer casing having .a central portion andsegmental yslots in the walls thereof through which said arms passytopermit limited swinging movement of said arms relative to' saidcasing, rotatable bearingelementsv in said casing bore and providingseats for said arms so that said bearing elements turn with said armsrelative to .Seid casina and all 'adjustable clamping element secured tosaid casing `'andacting on one of said arms for .moving the same towardsaid other .arm to clamp said arms and said bearing elements in adjustedposition relative to said casing.

7. zIn a .drawing instrument .o f the character described, a pair .ofrelatively Iadjustable .arms vof `solid cross section throughout A'theirlength, and a pivot and clamp device including a pivot box arrangedexternally of Vsaid arms and -having openings in the side walls thereofthrough which said arms pass, and a single adjustable element associatedwith said .pivot box 'for rmoving said arms together vfrictior'ially tohold said arms in adjusted .posi-tion in vstationary .relation with refspect to said pivot'box.

` instrument of the .character described, a pair `'ofielativelyadjustable arms of solid cross section throughout their length, and apivot and clamp device including a pivot box arranged externally of saidarms and having openings in the side walls thereof through which saidarms pass, rotatable bearing elements in said pivot box one for eacharm, and a single clamping device associated with said pivot box formoving said arms together and holding said bearing elements againstrotation thereby frictionally to secure both arms in adjusted positionrelative to said pivot box.

9. In a drawing instrument of the character described, a pair ofrelatively :adjustable arms, one of which has graduations on its outerside to provide a scale, and a pivot and clamp device providing a pivotfor said arms and iadjustably engaging said arms for effecting settingof the pivot clamp and including a rotatable adjustable element forsecuring said arms in adjusted position, said rotatable adjustableelement having an axial opening therethrough to provide sight of one ofsaid graduations when the same is positioned centrally of said opening.

10. In a drawing instrument of the character described, an arm havinggraduations along one side thereof, and an external arm clamp includinga rotatable adjustable screw element formed with an axial sight openingso that one of said graduations which lies centrally of said opening maybe readily observed.

l1. In an instrument of the character described, a pair of divider arms,a pivot and clamp casing having openings through its side walls throughwhich said arms pass, one of said openings being laterally elongated topermit relative swinging adjustment of said arms, and a single clampingelement secured to said casing and adjustable frictionally to clamp saidarms against axial movement and to resist swinging movement thereofrelative to said casing.

12. In an instrument of the character described, a pair of relativelyswingable and axially adjustable divider arms of solid cross section, acasing having a central bore, said casing having openings through theside walls thereof through which said arms pass and one of said openingsbeing laterally elongated to permit relative swinging adjustment of saidarms, arm-pivot means in said casing-bore, said pivot means turning insaid bore with one of said arms during such relative swinging armadjustment, and a single clamping screw threaded in said bore forfrictionally clamping said arms against axial movement and to resistturning movement of said pivot means relative to said casing.

13. In a drawing instrument of thecharacter described, a pair ofrelatively adjustable arms of solid cross section throughout theirlength, and pivot and clamping means arranged externallyof said arms andincluding an outer casing unit having openings through its side wallsthrough which said arms pass, one of said openings being laterallyelongated to permit relative swinging adjustment of said arms with saidarms in said elongated opening swingable relative to said casing unit.

14. In a drawing instrument of the character described, a pair ofrelatively adjustable arms of solid cross section throughout theirlength, and pivot and clamping means arranged externally of said armsand including an outer casing unit having openings through its sidewalls through which said arms pass, one of said openings being laterallyelongated to permit relative swinging adjustment of said arms with thearm in said elongated opening swingable relative to said casing unit,and a single clamping element adjustably secured to said casing formoving one of said arms towards the other to clamp both arms in adjustedposition relative to said casing.

15. In a drawing instrument of the character described, a pair ofrelatively adjustable arms, an outer casing having a central bore andopenings through the side walls thereof through which said arms pass,one of said openings being laterally elongated to permit relativeswinging adjustment of said arms with the arm in said elongated openingswingable relative to said casing, a bearing element mounted in saidbore to rotate relative to said casing and providing a seat for one ofsaid arms, and a clamping nut threaded within the casing bore for movingone of said arms toward the other to clamp both arms and said bearingelement in adjusted position relative to said casing.

16. In a drawing instrument of the character described, a pair ofrelatively adjustable arms, an outer casing having a central bore andopenings through the side walls thereof through which said arms pass,one of said openings being laterally elongated to permit relativeswinging adjustment of said arms with the arm in said elongated openingswingable relative to said casing, a combination spring and pivot diskarranged in said casing bore between said arms, and a clamping nutthreaded in said bore for moving one of said arms toward the other tocompress said springdisk to the desired degree thereby to hold both armsin adjusted position relative to said casing.

17. In a drawing instrument of the character described, a pair ofrelatively adjustable arms, one of Which has graduations along its outerside to provide a scale, and an adjustable pivot providing and clampingdevice arranged externally of said arms for providing a pivot for saidarms and adjustable to prevent relative pivotal movement of said arms,said device including an element adjustable to provide a setting of thearm pivot and provided with a sight opening located centrally of saidpivot providing and clamping device so that one of said graduationswhich lies centrally of said opening may be readily observed.

JOSEPH F. JOY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 179,793 HOW July 11, 1876 283,907Low Aug. 28, 1883 540,809 Bye et al June 11, 1895 FOREIGN PATENTS NumberCountry Date 8,282 Great Britain Apr. 9, 1902 149,860 Germany Mar. 29,1904 202,134 Germany Sept. 26, 1908

